The present invention relates generally to the field of catheters. More specifically, the present invention relates to dilation catheters for use in administering treatments to relieve a stenotic region or to widen a constricted blood flow or tubular passage, such as the coronary artery, as well as other vessels.
Percutaneous transluminal coronary angioplasty (PTCA), a procedure for treating a patient having a stenosis or constricted blood region in a coronary artery, has become a widely accepted therapeutic alternative to coronary arterial bypass surgery for many patients. PTCA increases the lumen by radial expansion. The main advantage of the PTCA procedure is in reducing morbidity and avoiding the immediate post-operative discomforts associated with coronary bypass surgery.
However, the benefits of PTCA are restricted to those lesions accessible to the balloon dilation catheter. With standard balloon systems, certain lesions are inaccessible due to variations in the patient's anatomy and vasculature. Further, seducing side branches, tortuous vessels, and the more distal arteries have presented serious difficulties in the PTCA procedure because, due to its length, the balloon could not reach the stenotic region.
When considering angioplasty as a method of treating stenotic regions, the morphology of the lesion is critical in determining whether the vessel will adequately dilate. If the stenosis is comprised primarily of fatty deposits, for example, it is possible to compress the stenosis radially outwardly, against the adjacent vessel wall, so as to increase the cross-sectional area of the vessel, and provide adequate perfusion through the vessel. If, however, the artery is hard, or the stenosis has calcified, the artery may be dissected if inflated with a standard dilation balloon.
Performing a coronary angioplasty involves the difficulty of inserting a balloon catheter into the desired coronary artery. Most balloon catheters are too flexible for direct insertion into the patient's coronary artery. Accordingly, the standard angioplasty process begins with the insertion of a guide wire into the obstructed vessel, under local anesthesia. A guiding catheter, or sleeve is then slipped over the wire. The guiding catheter is designed to provide a conduit through which a balloon catheter is passed. The tip of the guiding catheter is not tapered so as to permit the unimpeded passage of the balloon catheter therethrough.
The lesion may be approached with a guide wire by advancing the catheter and guide wire as a unit, or by advancing the guide wire first. Steering the tip of the wire is done by the surgeon or by an assistant. If the tip is moving in an undesired direction, then slightly withdrawing and torquing the guide wire will rotate the tip toward in desired direction. Once the wire is positioned, the balloon catheter may be advanced over the wire until it crosses the lesion. The balloon advances until it reaches the tip, which the surgeon has maintained in a fixed position in the distal artery. The cardiologist positions the balloon in the artery, expands the balloon, and then allows the balloon to depressurize to permit measurement of blood flow across the stenosis.
The benefits of angioplasty are restricted to lesions accessible to the balloon dilation catheter. With currently available balloon systems, (2 mm or longer in length) certain lesions are inaccessible due to variations in the patient's anatomy and vasculature. Further, seducing side branches, tortuous vessels, and the more distal arteries have presented serious difficulties in the PTCA procedure because, due to its length, the balloon can not effectively seduce these stenotic regions.
These difficult areas include, (1) the area immediately after the left main artery, in which there is a narrowing of the left anterior descending artery (LAD), (2) those areas of the heart where acute angled branching occurs along a bend in the artery, (3) lesions near the origin of the aortic artery and (4) bifurcation lesions. These special and difficult situations cannot adequately be treated with long catheters. Seducing such tortuous vessels is quite difficult using the standard, longer dilation balloons.